| Soy sauce is a kind of indispensable condiment in China, and the wastewater produced inthe production process of soy sauce is large. It is characterized by high biochemical oxygendemand, high chemical oxygen demand and heavy chromaticity but with goodbiodegradability. During the process of the treatment of soy sauce wastewater, the pigmentsubstance in wastewater is hard to be removed from synchronization with the degradation oforganic pollutants because of its high molecular weight and complicated structure, and furtherreverse color may happen under condition of oxygen, so it is necessary to use other physicalor chemical techniques such as air float, activated carbon absorption and chemical depositionand so on to decolorize except for biological treatment system, but these techniques arecomplicated and increase the cost of the whole process. Therefore, color removing is both keypoint and difficulty in the treatment of soy sauce wastewater, and this research has importantpractical significance.Based on the object of soy sauce wastewater, this study focused on the decolorizationexperiment using the combined technique of anaerobic process of ABR with segmented andmultiphase and aerobic process of SBR. The characteristics in the starting and running state ofABR were investigated. The degradation rules of pigment substance and COD under thetreatment of soy sauce wastewater were also studied. The mechanism of decolorization andthe best operating conditions of ABR were discussed. The results of the experimentdemonstrated that: The start-up of ABR was made under the conditions of (35±1)℃, and thestartup mode were low load and low increase. The color removal rate wasbetween25.6%and50.2%, and the COD removal efficiency could be remained above91%.The first and the second compartment had the main removal of color, and the thirdcompartment had smaller role of decolorization. During the operation of the ABR, the colorremoval rate was between29%and45.1%, and COD remove rate was more than88%. Colorremoval reduced with HRT shortening gradually, but it had little effect on COD removal, andCOD removal rate was up to95.3%when the HRT was20h.The SBR reactor inlet was ABR outlet, and the stability of the reactor which treated soysauce wastewater was investigated. The remove law of color, COD, NH3-N and TP wereanalyzed under different aeration time, and the mechanism of anti-color was investigated. The results of the experiment demonstrated that: Aeration for2h, the effluent of COD, NH3-N andTP was declined rapidly, while the color increased; aeration for4h, the removal rate of color,COD, NH3-N and TP were up to74.5%,15%,75%and66.8%above, respectively; and theyhad little change with extension of the aeration time after4h. Combined with energyconsumption and actual operation, the optimum aeration time was4h.Decolorization effect of soy sauce wastewater treatment was studied by ABR-SBRcombined process, and the operating characteristic of the combination process wasinvestigated. During the operation of the ABR-SBR combined process, the color removal ratewas about46%, and COD removal rate maintained at above96%. The removal rate ofNH3-N and TP reached80%or more.In addition, the sludge performances of the two reactors were studied in the article.During the soy sauce wastewater treatment process, the sludge had uneven surface in the threecompartments of ABR, and the color changed gradually from gray to black. Particle size andsedimentation rate of sludge were than those inoculated with sludge, and sludge structuretended to dense. Bacteria bacillus, bacteria, filamentous bacteria were almost on the wholesurface of sludge, and they were connected to a network; The sludge in the SBR showedbrown and had a good settling characteristics. Short bacilli and cocci were mainly on thesurface of sludge, and the dense surface rendered showed braided. |
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